<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>test</title>
</head>
<body>
<div style="text-align:center">
<video id="video" width="320">
  <source src="http://video19.ifeng.com/video09/2016/09/01/4227033-102-078-2151.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>
</div>

<div style="text-align:center">
<button onclick="playPause()">播放/暂停</button>
<button onclick="big()">放大</button>
<button onclick="small()">缩小</button>
<button onclick="reset()">还原</button>
</div>
<script type="text/javascript">
	var myVideo;
	myVideo = document.getElementById('video');

	function playPause() {
		if (myVideo.paused) {
			myVideo.play();
		}else{
			myVideo.pause();
		}
	}

	function big() {
		myVideo.width = 640;
	}

	function small() {
		myVideo.width = 160;
	}

	function reset() {
		myVideo.width = 320;
	}
</script>
</body>
</html>